Conventionally, metallic wiring boards in which wiring based on a metallic pattern is formed on the surface of an insulative substrate have been widely used for electronic parts and semiconductor devices.
A “subtractive method” is mainly used for producing such a metallic pattern-bearing material. The subtractive method includes providing a photosensitive layer, which is sensitized by irradiation with actinic rays, on a metal film formed on a substrate surface, subjecting the photosensitive layer to imagewise exposure, developing the photosensitive layer to form a resist image, etching the metal film to form a metallic pattern, and finally peeling off the resist.
In the metallic pattern obtainable by this method, adhesion between the substrate and the metal film is generated by an anchor effect, which occurs as a result of providing roughness to the substrate surface. However, this has been problematic in that roughness at a substrate interface of the metallic pattern is a cause of poor high frequency properties when the metallic pattern is used as metallic wiring. Furthermore, in order to impart roughness to the substrate surface, the substrate surface must be treated with a strong acid such as chromic acid, which makes it necessary to perform complicated processes in order to obtain a metallic pattern which has excellent adhesion between the metal film and the substrate.
To address these problems, there has been proposed a method of improving adhesion between a substrate and a metal film by performing a plasma surface treatment, including introducing a polymerization initiating group to the substrate surface, and polymerizing a monomer through the polymerization initiating group, thereby generating a surface-grafted polymer having a polar group at the substrate surface, without roughening the surface of the substrate (see, for example, Non-Patent Document 1). However, since in this method the graft polymer has a polar group, absorption or desorption of moisture tends to occur according to changes in temperature or humidity, and as a result, the metal film or substrate tends to be deformed.
Moreover, when the metallic pattern obtained by this method is used as wiring of a metallic wiring board, the graft polymer having a polar group remains at the substrate interface, and is likely to retain moisture, ions or the like, raising concerns with respect to the level of influence of temperature or humidity, resistance to ion migration between wiring, and deformation of wiring. In particular, when the metallic pattern is to be applied to microwiring of printed wiring boards or the like, high insulating properties are required between wiring (metallic patterns), and further improvement of inter-wiring insulation reliability is demanded.
Photocurable resin compositions, due to their excellent characteristics, are used in not only materials for surface treatment applications as described above, but also in resist materials, materials for printing plates, coating materials, materials for rapid prototyping, and the like. A photocurable resin composition which is cured by radical polymerization is generally composed of a binder, a polyfunctional monomer and a photopolymerization initiator. In this case, a binder which has a polymerizable group is used in a technique for enhancing photocuring sensitivity.
Surface treatment materials, particularly those for forming plating films, are required to have a function of adsorbing a plating catalyst. In general, a carboxylic acid group, a hydroxyl group, an ether group and the like are known as groups capable of adsorbing a plating catalyst, but since these functional groups have high hydrophilicity and are prone to hold moisture, ions or the like, there are concerns that their use may result in an undesirable level of influence of temperature or humidity on a plating film, or deformation of the plating film.
In response to these concerns, a method of using a cyano group (nitrile group) as a functional group which provides both satisfactory adsorption of a plating catalyst and satisfactory hydrophobicity, is being considered.
As a polymer having the above cyano group and also a polymerizable group, products synthesized by anion polymerization of the following monomer are known (see, for example, Patent Document 1).CH2═C(CN)COOR1OOCCH═CH2 (R1 is a lower alkylene group)
However, in this synthesis method, anionic polymerization proceeds even with a trace amount of moisture, and handling is difficult.
As another example, Patent Document 2 describes the following macromonomer.

However, since the above macromonomer has few polymerizable groups in the polymer, curability (polymerizability) is low, and since the cyano group content in the polymer is low, there are concerns about adsorbability with respect to a plating catalyst.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 11-106372
Patent Document 2: JP-A No. 2004-176025
Non-Patent Document 1: Advanced Materials, No. 20, pp. 1481-1494 (2000)